The derivatives of rhein of particularly of diacetylrhein are drugs endowed with a relevant antiarthrosic, analgesic and anti-inflammatory activity (Italian Patent No. 1098332).
The present invention relates to a number of formulations for oral use with slow release of dyacetylrhein and other derivatives of rhein for therapeutical purposes.
It is known that the more widespread solid pharmaceutical forms for oral use with delayed release of active ingredients may be reconducted to the following schemes:
(a) comminution of the drug in particles of very small size by supporting them onto nuclei of inert substances. The microgranules thus obtained are thereafter coated with particular excipients (fatty substances and natural or synthetic waxes, plastic substances, etc.) so as to afford to the microgranules different rates of drug release.
(b) Absorption of the drug onto suitable supports, (polymers, synthetic resins, etc.) so as to obtain insoluble complexes from which the active principle is gradually and slowly eluted under the action of the several biological factors of the gastro-enteric tract, such as pH, enzymatic activities, electrolytic concentration, etc.
(c) Supporting onto an inert matrix capable of slowly swelling within the gastro-enteric duct (chemically modified celluloses, polysaccharides, etc.) thus permitting the release of the drug in a gradual manner by diffusion.
(d) Mixed technologies among those listed above which permit, as well, the delayed release of the drug.